1. Field of the Invention
The present invention relates to a light-emitting display device, and more particularly, to a circuit and method for driving a self light-emitting display device which itself emits light when an electric or other energy is inputted thereto.
2. Discussion of the Related Art
Generally, a light-emitting display device is classified into a passive light-emitting display device and an active light-emitting display device.
The typical passive light-emitting display device is a liquid crystal display (LCD). The passive light-emitting display device basically has a limited brightness against area, and has a problem in displaying a moving picture due to a relatively slow response speed. Also, the passive light-emitting display device has a limited angle of view.
The active light-emitting display device has been developed to overcome the drawbacks of the passive light-emitting display device.
The active light-emitting display device emits light for itself when the electric or other energy is inputted, and is known as a self light-emitting display device.
The self light-emitting display device may be a light-emitting diode (LED), cathode ray tube (CRT), plasma display panel (PDP), electroluminescence (EL), field emission display (FED), etc.
This self light-emitting display device has an excellent visual recognition in a place where an external light is not so bright, and has a simple circuit construction in comparison to the LCD.
For the above-described advantages, the spread of self light-emitting display device is gradually increasing.
However, according to the conventional technology, the contrast ratio of the self light-emitting display device is considerably lowered in a place where the external light is very bright. This causes the visual recognition to become deteriorated. In detail, in a place where the external light is quite bright, the visual recognition of the self light-emitting display device is considerably lowered in comparison to a reflective LCD that is an active light-emitting display device.
This problem limits the outdoor use of the display devices using the self light-emitting display devices.
In order to overcome the deterioration of the visual recognition of the conventional self light-emitting display devices, the power to be supplied to the devices should be heightened by increasing luminance of the panel of the light-emitting display device. That is, in order to keep an excellent visual recognition in an environment where a strong light is incident from the outside, the light-emitting display device should be turned on with a great brightness.
However, since the permissible applied voltage of the self light-emitting display device is limited in consideration of its efficiency and lifetime, it is not preferable to heighten the power by increasing the luminance without reason.